High Degree of Mitochondrial 3243 Mutation in Gastric Biopsy Specimen in a Patient With MELAS and Diabetes Complicated by Marked Gastrointestinal Abnormalities

A point mutation of mitochondrial DNA at nucleotide position 3243 has been shown to cause mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) (1). This mutation, however, is also found in maternally inherited diabetes and deafness (MIDD) (2), which accounts for ∼1% of the diabetic population in Japan (3). The same point mutation of mitochondrial DNA causes a wide range of symptoms that have been suggested to be due to the difference in the degree of heteroplasmy; thus, the proportion of the mutant mitochondrial DNA is divergent among different tissues (4). Little evidence, however, is available …